Season 5 Episode 6 - Natale Carol (1) 

On her Natale vacation with her brother's family, Scully receives a mysterious phone call from a familiar voice. The phone call leads Scully to a murder case where the victim's adopted daughter bears an uncanny likeness to Melissa at that age.
parole chiavi: x-files, scully, mulder, full episode, season 5, episode 6, 5x06, Natale carol (1)